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EVALUATION OF THE C-TERMINAL CROSS-LINKED TELOPEPTIDE OF TYPE II COLLAGEN (CTX-II) AS A POTENTIAL CARTILAGE BIOMARKER FOR USE IN THE HORSE
Mack S.J2, Jackson B.F1, Dyson P.K2, Verheyen K.L.P2, Price J.S1.
Departments of Veterinary Basic1 and Clinical Sciences2, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, AL9 7TA.
Aims: To assess a new type II collagen degradation product, the C-terminal crosslinked telopeptide of type II collagen (CTX-II), as a potential biomarker for detecting equine cartilage degradation. This biomarker has been shown to be valuable for assessing cartilage damage in human osteoarthritis but has yet to be investigated in horses.
Methods: Concentrations of CTX-II were measured using a human ELISA (Nordic Bioscience Diagnostics A/S, Denmark). Species cross-reactivity was established by serial dilution of equine serum against the assay standard curve. CTX-II concentrations were measured in serum of horses aged between 6 months and 20 years and in samples collected monthly from twelve 2 year old Thoroughbreds over a flat race season. Six had been diagnosed with carpal injury during the training season (cases), and six (controls) had never missed training due to any type of musculoskeletal injury. Carpal injuries were defined as an episode of lameness localised to the knee by various diagnostic means which resulted in the horse missing at least 4 consecutive training days.
Results: The assay displays excellent species cross-reactivity and serum concentrations of CTX-II decreased significantly with age (R= -0.88, P<0.01). There was a significant effect of carpal injury (P=0.044) and time (P=0.0001) on CTX-II concentrations over the training season, with a significant difference between injured and non-injured groups in February (P=0.009). CTX-II concentrations were also significantly higher in the cases when the groups were compared two months prior to the onset of lameness (P=0.04) and in the first reported month of injury (P=0.009).
Conclusion and Practical Significance: These results suggest that CTX-II is a potentially useful serum biomarker for monitoring cartilage degradation in horses. In the long term the method may be used to for the early detection of cartilage damage and thus enable better management of joint injury cases.
BVetMed Final Year Elective Project presented by Sarah Mack (smack@rvc.ac.uk) at the British Equine Veterinary Association (BEVA) Congress 2007
